This invention relates to an injection unit of the injection machine, which is particularly equipped with a pressure sensor for feedback of a signal so as to control injection operation of the injection machine more precisely.
In order to monitor and control injection operation effectively and heighten stability and reliability thereof, a load bearer is usually applied in an injection machine for sensing the injection forward and back pressure during injection operation. More particularly, for driving a servomotor, signal of the load bearer is necessary for control of the injection pressure, the back pressure, and the release-to-retreat force of the injection machine.
In an xe2x80x9cauger and injection structurexe2x80x9d widely implemented in existing injection machines as shown in FIG. 1, a load bearer 39 is arranged to sense the injection gel""s pressure and the back pressure effectively, and a release-to-retreat path (A) and a gel-injection path (B) are shown in FIG. 2. In this structure, a bearing seat 371 is fixedly locked on a depression base 391, which is locked together with the load bearer 39 and locked directly on a movable depression plate 23 to incur a pressure imposed to the load bearer 39 at the very beginning, thereby and along with a clearance made during assembling, the pressure sensed by the load bearer 39 will somewhat depart from the due value to have badly affected machine""s stability and reliability, or the load bearer 39 may become insensitive in response and for output of a correct signal. Moreover, when an auger 17 is driven by a belt pulley 42 to rotate and feed material between a bearing base 46 and the depression plate 23, the sensed value cannot be read from the load bearer 39 directly to result in distortions or errors. Consequently, neither can an output pressure be reckoned precisely, nor can a successful feedback control be made accordingly.
The primary object of this invention is to provide a sensing and reckoning mechanism equipped with a load bearer that can sense injection gel""s pressure and reckon back pressure of an injection machine precisely.
For more detailed information regarding advantages or features of this invention, at least an example of preferred embodiment will be elucidated below with reference to the annexed drawings.